But Collins could be a drag on the GOP ticket nationally, as Democrats seize on his insider trading case to convince voters to put them in power.

Collins was the first member of Congress to endorse President Trump and had been considered a shoo-in for reelection in his heavily Republican district outside Buffalo. News of the indictment helped energize his Democratic challenger, Nate McMurray, who suddenly found himself surrounded by a boisterous group of supporters at a UAW hall.

"If I look a little surprised, not too long ago we had a press conference here and nobody showed up," McMurray joked.

Even with the indictment, Collins remains a heavy favorite in the race, but Democrats say the charges against him reflect a broader "culture of corruption" in the GOP.

The party used a similar campaign a dozen years ago to successfully take control of Congress, and that year 74 percent of voters told pollsters that corruption and ethics were either "very" or "extremely" important to their vote in the wake of a series of Republican ethics scandals.

"Democrats don't need to defeat Chris Collins in order to get to the majority," said Nathan Gonzales, editor of Inside Elections. "But his indictment is keeping Republicans on the defensive in the news."

Indeed, Democrats quickly seized on Collins' troubles as another example of ethical blinders in the GOP, which have already cost the jobs of three Trump cabinet members and driven several members of Congress into retirement.

To be sure, neither party has a spotless record in this area. Sen. Bob Menendez, D-N.J., is seeking reelection after his bribery trial ended in a hung jury last year, and an official rebuke from his Senate colleagues. But Democrats successfully used GOP scandals in 2006 as a stepping stone to regain majorities in both the House and Senate.

Chicago Mayor Rahm Emanuel, who as a congressman led the committee charged with electing House Democrats that year, criticized Republicans back then for what he called a "culture of corruption."

"It was a kind of genius slogan because anything anyone on the Republican side did wrong was kind of lumped under this umbrella," Gonzales recalled.

Nancy Pelosi, who became House speaker after Democrats took the majority, summed up their strategy that year with a memorable phrase.

"You cannot advance the people's agenda unless you drain the swamp that is Washington, D.C.," Pelosi said in 2006.

A decade later, that slogan was famously co-opted by Donald Trump as he ran for president. But Rep. Cheri Bustos, D-Ill., who is part of the committee working to elect Democrats this year, complained that, far from draining the swamp, Trump built a hotel on it. And he went on to pocket more than $40 million from his Washington hotel last year.

"We're here to serve the public," Bustos said. "And if somehow people are getting rich off their position, then we ought to take a deeper look at that."

Democrats promise that if they do regain their majorities in Congress, they'll push for stronger ethics legislation, including a requirement that the president sell off his business holdings.

If Democrats can make that case stick, the charges against Collins could have ripple effects far beyond his suburban New York district.

"I'm not convinced the average voter in Iowa or California is going to hold the Republican candidate responsible for what Congressman Collins did," Gonzales said. "But if it adds to the general sense that there needs to be a change, then I think it could benefit Democratic candidates."

Gonzales thinks Democrats have a better than even chance to win the House this fall, though the Senate remains an uphill climb. Copyright 2018 NPR. To see more, visit http://www.npr.org/.